Research Of Spectrum Detecting System Based On Diffraction Grating And Detector Array

The resolution, accuracy, stability and the other factors of the spectrum detection system are important indicators to its performance evaluation. The errors of detection system will not only reduce the detection resolution, but also cause the inaccurate detection results.Under the background of fiber Bragg grating demodulation, taking the spectral detection system which based on the diffraction grating and detector array as the research object, this paper analyzed the optical aberrations, spectral sampling errors and spectroscopic system response which in the system, and proposed an improvement method to improve the detection performance of the system.The main research work of this paper has the following points:(1) Based on the optical design principle and aberration analysis theory, the optical structure of the spectrum detection system has been designed by Zemax software. A transmission type diffraction grating structure is designed, which can enlarge the diffraction angle, reduce the size of the space, and improve the resolution to meet the design requirements of the system. The assembly tolerance of optical path system is given, and the influence of tolerance on the system is analyzed.(2) Based on the wavelength demodulation method by spectrum detection system, the influence of spectral sampling on the demodulation results is analyzed and simulated by Matlab. The variation law of error is obtained by analyzing the simulation which include the sampling position, sampling interval and sampling integral three factors.(3) By experimental method, the influence of the spectral response of the spectrum detection system on the system detection is explored. By analyzing the laser light source measured value by spectrum detection system and optical wavelength meter, the compensation curve of spectral response function is fitted by the Matlab software. Based on the analysis of the experimental results, the spectral response errors are corrected. Finally, the demodulation of FBG is simulated and measured, and the reliability of the system is verified.By studying the spectral detection system based on the diffraction grating and detector array, the factors which affect the system detection are analyzed, and the compensation method of detection errors or the improvement of system design are proposed. This topic provides a theoretical basis for improving the measurement resolution and accuracy of the spectral detection system, which has a certain reference value for the study of the spectral detection system in the future.